Recently, touchpads have been widely used in various electronic products due to their simple structure, light weight and low cost to replace conventional input apparatus. Generally, there are touchpads operated in two-dimensional mode and touchpads operated in one-dimensional mode. FIGS. 1A and 1B show two conventional sensors 100 and 101 with typical shapes for a touchpad of two-dimensional mode, each of which has a plurality of horizontal traces 102 and vertical traces 104. When a finger touches the two-dimensional touchpad, the traces 102 and 104 where is touched transfer a corresponding signal representative of the coordinate of the touched position to a host connected with the two-dimensional touchpad. The host may respond to the received signal based on the coordinate difference in the movement of the finger.
However, when a horizontal or vertical movement of the finger is desired, a two-dimensional touchpad cannot provide accurate control. For example, as shown in FIG. 2, when a horizontal scroll bar of a window is to be scrolled rightward, a finger 106 will move horizontally from left to right on a two-dimensional touchpad 105, while during the movement, the finger 106 might shift upward or downward slightly, causing the vertical scroll bar also to scroll upward or downward together with the scrolling of the horizontal scroll bar.
U.S. patent application publication No. 20040252109 provides a one-dimensional sensor for a touchpad, which senses the movement of a finger as counterclockwise or clockwise and generates a corresponding signal for the reaction in response thereto, such as upward or downward movement, left or right movement, and addition or subtraction operation. Thus, an uneven spinning degree does not affect the judgment of the instruction. Even such one-dimensional touchpad could accurately determine a positive or a negative direction, it cannot provide a multiple functions such as handwriting recognition, as a two-dimensional touchpad. If any extra function is required, an extra button or other input apparatus has to be added to the device and thus the cost is increased.
Therefore, it is desired a touch-sense apparatus available for one-dimensional and two-dimensional modes.